module 3 - 7.2 mammalian gaseous exchange system Flashcards

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1
Q

what do all organisms require?

A

nutrients
the ability to excrete waste

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2
Q

how do many simple organisms exchange substances?

A

directly across their external surfaces

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3
Q

why do large organisms require specialised gas exchange and transport systems?

A

to transport substances (oxygen, nutrients) to their cells efficiently

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4
Q

how do fish exchange substances?

A

across their gills

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5
Q

how do insects exchange substances?

A

openings on their surfaces called SPIRACLES

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6
Q

where does gas exchange occur in mammals?

A

lungs and a part of the alveoli

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7
Q

why are all inner exchange surfaces moist?

A

because O2 (& some CO2) needs to be changes into aqueous solutions and needs O2to get into cells

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8
Q

why do land animals face a constant battle between ventilation, gas exchange, and retaining water?

A
  • gas exchange surfaces are moist to aid diffusion by oxygen dissolving in water
  • ventilation causes this water to readily evaporate
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9
Q

what is breathing? (in terms of ventilation)

A

ventilation of the lungs

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10
Q

how are the lungs and ribcage stuck together?

A

outside surface of lungs stuck to inside membrane of ribcage

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11
Q

what is the pleural membrane?

A

the double membrane that the lungs are enclosed in

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12
Q

what is the pleural cavity?

A

the space between 2 membranes and is filled with small amount of pleural fluid

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13
Q

what does the pleural fluid do?

A
  • lubricates the lungs
  • adheres to outer walls of the lungs to thoracic cavity by water cohesion
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14
Q

how is the pleural fluid connected to the membrane

A

hydrogen bonding

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15
Q

what are three important functions of the nasal cavity?

A
  • large SA and good blood supply
  • hairy lining
  • moist surfaces
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16
Q

why is a large SA and good blood supply, an important functions of the nasal cavity?

A

warms the air as it passes into the body

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17
Q

how is hairy lining an important function of the nasal cavity?

A

hairs trap dust & bacteria in mucus & prevent them from reaching lungs causing infection

18
Q

how is moist surfaces an important function of the nasal cavity?

A

increases humidity of incoming air, reduces evaporation of water in lungs

19
Q

what is the structure of trachea?

A
  • supported by layer of cartilage that holds trachea open and prevents collapse
  • rings are incomplete - allows it to bend when food swallowed down oesophagus
  • lined with ciliated epithelial & goblet cells that prevent dust & bacteria
20
Q

what do goblet cells do?

A

secrete mucus made of mucin, keeps airways clear

21
Q

what do the ciliated epithelial cells do?

A

beat regularly to move micro organisms and dust particles along the mucus

22
Q

what are the bronchus?

A
  • bronchus are extensions of trachea - split in 2 for left and right lung
  • very similar structure to trachea but smaller
  • cartilage rings hold pipe open
23
Q

what are the brochioles?

A
  • bronchus split into smaller bronchioles
  • no cartilage and held open by smooth muscle
  • when muscle contracts, bronchioles contract (dependent on air flow)
  • lined with thin layer of epithelial tissues
24
Q

what is the alveoli?

A
  • little air sacs, most gas exchange occurs
  • made of thin layer of flattened epithelial cells, and some collagen and elastic fibres
  • the elastic fibres cause recoil - helps move air out of alveoli
25
Q

what are 4 features of efficient gas exchange?

A
  • large SA
  • thin layers
  • constant blood supply
  • ventilation
26
Q

how is a large SA a feature of efficient gas exchange?

A

large area for exchange of materials to occur

27
Q

how is thin layers a feature of efficient gas exchange?

A

creates a short diffusion path for gases, increases speed of exchange

28
Q

how is good, constant blood supply a feature of efficient gas exchange?

A
  • maintains large diffusion gradient
  • ensures exchanged substances are constantly moving
29
Q

how is ventilation a feature of efficient gas exchange?

A

maintains the diffusion gradient, faster & more efficient

30
Q

what happens to the chest volume during inhalation?

A

chest cavity increases in volume, lowering pressure in the lungs

31
Q

what does the decrease in pressure during inhalation lead to?

A
  • leads to a tendency for the lungs to collapse
  • alveoli lacks support from cartilage
32
Q

what is a lung surfactant?

A

a phospholipid that coats surfaces of the lungs

33
Q

what happens without the lung surfactant?

A

watery lining of alveoli creates surface tension, causing them to collapse

34
Q

why do animals need to maintain a concentration gradient across their exchange surfaces?

A
  • so oxygen will diffuse into the blood and carbon dioxide will diffuse out
  • maintained by ventilation
35
Q

how do fish manage to maintain a concentration gradient across exchange surfaces?

A

keeping a continuous stream of oxygenated water moving over their gills

36
Q

how does ventilation occur?

A

pressure changes in the thoracic cavity

37
Q

what does the rib cage provide?

A

a cage where pressure changes to facilitate breathing

38
Q

what is inspiration?

A
  • breathing in
  • causes lungs to move up and out
39
Q

what active processes are caused when inspiring?

A

diaphragm - moves down
intercostal muscles - moved the ribs up and out
thoracic volume - increases
thoracic pressure - decreases
air flow - INTO the lungs

40
Q

what does air flow in to/ out of the lungs during inspiration/ expiration ?

A

to equalise pressure difference

41
Q

what passive processes are caused by expiration?

A

diaphragm - moves up
intercostal muscles - moves the ribs down and in
thoracic volume - decreases
thoracic pressure - increases
air flow - OUT of the lungs